Overspeed cutoff for internal combustion engine



M. HOFER March 5, 1957 OVERSPEED CUTOFF FOR INTERNAL COMBUSTION ENGINE Filed March 31, 1954 2 Sheets-Sheet 1 7 I i i r! INVENTOR MAX HOFER WWI? ATTORNEYS M. HOFER March 5, 1957 OVERSPEED CUTOFF FOR INTERNAL COMBUSTION ENGINE Filed March 51, 1954 2 Sheets-Sheet 2 i INVENTOR MAX HOFER aY MM.;@ :52

ATTORNEYS United State Patent .2

OVERSPEED CUTOFF FOR INTERNAL COMBUSTION ENGINE Max H ofer, Augsburg, Germany, assignor to Maschineufabrlk Augsburg-Numberg A. G., Augsburg, Germany, a .corporation of Germany Application March 31, 1954, Serial No. 420,089 Claims priority, application Germany April 4, 1953 13 Claims. (Cl. 123-198) This invention relates to a device for automatically interrupting the fuel and air feeds to an internal combustion engine when the speed of the engine exceeds a predetermined number of revolutions per minute.

In many applications of internal combustion engines, it is-desired to provide a device for stopping the engine or cutoff fuel and/ or air fed thereto automatically when the speed of the engine exceeds a certain amount. For example, if the clutch mechanism connecting the engine to a load were to break down while the engine is operating near its full load capacity, the engine would then race at a no-load full-throttle setting with, perhaps, serious damage to the engine parts. If, however, it is attempted to provide such an overspeed cutoff by connecting the fuel and air feed controls to some type of overspeed governor through a mechanical linkage, considerable difliculties may arise. For example, if the fuel and air controls are widely separated on the engine, as is frequently the case, such linkage would be quite complicated, delicate to adjust properly, susceptible to slack and lost motion, and may occupy considerable space outside the engine.

According to the present invention, a hydraulic cutofi system is provided which is quick and positive acting, may be tailored to fit neatly about the outer contours of the engine with few protrusions therefrom, and the complexity of which is not appreciably increased wherever the fuel and air feed controls may be positioned on the engine.

Accordingly, a primary object of this invention is to provide a completely automatic hydraulic cutoff system for an internal combustion engine.

A further object of this invention is to provide a cutofi system of the character described which is positive and quick acting to interrupt fuel and air fed to an internal combustion engine automatically when the engine speed exceeds a predetermined amount.

Still another object is to provide such a cutoff device which, after having once been actuated, positively maintains fuel and air feeds closed until the device is manually released and reset.

A still further object is to provide in such a device, a manual control which may override the automatic control to provide a positive and immediate actuation of the cutoff device to stop the engine.

Another object of this invention is to provide a hydraulic cutoff device of the character described which is itself driven by the engine so that the cutoff will automatically be ready for actuation whenever the engine is running.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings,

Fig. 1 shows a side view of an internal combustion engine embodying the invention;

Fig. 2 is a somewhat diagrammatic view of the hydraulic circuit of the present invention and with certain parts shown in section;

Fig. 3 is a plan view of a portion of the circuit of Fig. 2; and

Fig. 4 is a partial section through the air cutoff members.

Referring to the drawing in which like reference nu merals refer to like parts throughout the several views thereof, there is shown an internal combustion engine having a crankshaft 1 which, in addition to providing the main power takeoff of the engine, drives a hydraulic pump 2 and an overspeed governor indicated generally at 3. Pump 2 draws hydraulic fluid'from a reservoir 25 and discharges it under pressure into a hydraulic conduit 8 which forms, as indicated in Fig. 2, a complete circuit ending back at the inlet to the pump. Included in this hydraulic circuit are a pair of cylinders 9, which are part of the air inlet control, and a cylinder 10, which is part of the fuel inlet control.

Hydraulic fluid under pressure from pump 2 acts against pistons 91 in cylinders 9 and piston 101 in cylinder 10.

The action of the hydraulic fluid'on pistons 91 and 101 is opposed by the actions of springs 92 and 102 respec tively, each tending to urge the pistons against the action of the hydraulic fluid.

As long as the hydraulic circuit is open and the hy- 2 cut off, the continued action of the pump will build up in cylinders 9 and 10 sufficient hydraulic pressure to force pistons 91 and 101 against the action of springs 92 and 102.-

Pistons 92, acting in cylinders 9, form a part of the air throttling system. Thus, levers 11 rotate about a pivot 12 under the influence of the movement of pistons 91 in-the cylinders 9. In operating position (i. e., with the engine running) levers 11 lock against bell cranks 13, which are fixedly mounted on shafts 15. In the position shown in Fig. 2, the levers 11 tend to lock bell cranks 13 and hold them against the action of springs 14, thus preventing the rotation of shafts 15. As shown in more detail in Fig. 4, shafts 15 carry air cutoff valves 16 which are disposed in the air induction passage 17 of the engine. Thus, upon the extension of pistons 91 from cylinders 9, as by building up enough hydraulic pressure in cylinders 9 to overcome the action of springs 92, levers 11 will pivot around the points 12 sufficiently to allow the springs 14 to move bell cranks 13 and rotate shafts 15 so that valves 16 move to cut oif the air passage 17 interrupting air fed into the engine cylinders.

For controlling the fuel feed, a cylinder 10 is provided;

also in the hydraulic circuit, and positioned adjacent the fuel control lever or throttle 19. Piston 101 operates in cylinder 10, and is urged into the position shown in Fig. 2 by the action of spring 102 in the absence of suflicient hydraulic pressure in cylinder 10 to overcome the action of spring 102. When such hydraulic pressure builds up in cylinder 10, however, piston 101 is moved along cylinder 10 until it strikes fuel control lever .19 to interrupt fuel feed in the engine cylinders.

Conduit 8 is connected to a passage 22 which leads to the inlet of pump 2. interposed in passage 22 is a plunger valve 7 which is urged toward closed position by a spring 20. The valve 7 is slidably mounted in a hollow member 27 formed in the cutoff device 3, and is held open in opposition to spring 20, as shown in Fig. 2, by a pawl 6 which is pivoted within a cut away portion 28 in the lower part of piston valve 7. Pawl 6 locks within a recess 29 in the lower wall of cylinder 27 to maintain the plunger valve 7 in raised position against the action of spring 20 and, thus, the passage22 open so that hydraulic fluid in conduit 8 isfree to return to the inlet of pump 2. A pin 5 is slidably mounted in the wall of cylinder 27 so that, upon depression ofthe pin.5,,it,Wi,1l

. Faten'ted Mar. 5, 195,'Z

suitc se and 6f as/'1 6 to dislodge the opposite end of pawl 6 from recess 29 so that the plunger valve 7 may close, under the action of spring 20, to close off passage 22 and prevent hydraulic fluid from flowing out of conduit 8 into the .inlet of pump 2.

An eccentric ring 4 is mounted within chamber 3% to berotated by crankshaft 1. A spring 40 holds the eccentric ring 4 c'oaxially about its shaft until the engine speed exceeds a predetermined amount, whereupon the force of spring 40 is overcome by the centrifugal force on the heavy side of eccentric ring 4- causing it to strike pin 5 and release pawl 6 so that the plunger valve 7 is closed by the action of spring 20 interrupting the hydraulic circuit.

Inaddition to the automatic ove'rspeed control or gove'rnor. provided by the aforementioned eccentric 4 to interrupt the hydraulic circuit, a manual cutofi is provide'd; Thus, a piston 23 in recess 29 will unseat pawl 6, allowing plunger valve 7 to close, when the piston 23 is moved to the right in Fig. 2. This is satisfactorily accomplished by admission of a pressure fluid behind piston 23 from a fluid pressure source 36 which is manually controlled by valve 24 and supplied through conduit 35 from any suitable source of hydraulic or air pressure.

a The operation of the device is as follows: During normal operation of the engine, the parts of the control system are in their operative positions as shown in Figs. 2 and 4. Upon overspeed of the engine, ring 4 begins to rotate eccentrically about shaft 1 and strikes pin 5, cansing pawl 6 to slip out of recess 29, and thus allowing spring 20 to close plunger valve 7. The hydraulic circuit is thereby broken, and the output pressure of pump 2 builds up in conduit 8, causing pistons 91 to overcome springs 92, and piston 101 to overcome spring 102. A pressurerelief bypass valve (not shown) is provided in the usual manner between the outlet and inlet of pump 2, to prevent excessive build up of pressure in the circuit above that pressure necessary to operate the cutod device.

Movement of pistons 91 against springs 92 causes levers 11 to unlock levers 13, and springs 14 cause these levers 13 to twist shafts 15, thus closing air cutofi valves 16 and interrupting the induction of air through passage 17. At the same time piston 101 overcomes spring 102 and strikes against regulating rod 19 to cut oif the fuel feed to the engine.

If the engine is equipped with a charging blower for providing air to the cylinders, the blower will still be supplying air under pressure to passage 17 since the engine will still be rotating at a relatively high speed.

Accordingly, in orderto relieve any excessive build up of pressure in passage 17 and to prevent undesirable heating up ofthe blower, bypass valves 18 are provided to relieve the rising pressure in passage 17, though not passing enough air to allow continued operation of the engine.

The cutoff system remains locked, and the engine can not be restarted until the button 21, which is connected to plunger valve 7, is pulled up to overcome spring 20 and allow pawl 6 to lock the valve 7 in open position. The air valves 16 must then be opened, and the fuel control lever set to the start position before operation of the engine can be resumed. It is therefore impossible for the engine to accident-ally start running once the cutolf system of the present invention has caused it to stop.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which i's'defined in the appended claims.

a What is claimed is: I

1. An automatic cutofl device for stopping internal combustion engines at a predetermined speed comprising in combination fluid pressure responsivethrottle means for interruptingfuel and air feeds to said engine upon application offluid pressure, means for supplying fluid pres:

enemas sure to operate said throttle means, means for limiting said fluid pressure at said throttle means to an inoperative amount, and control means responsive to the speed of said engine for interrupting the-action of said pressure limiting means when said predetermined engine speed is reached effecting increase" of said fluidpres's'ure to operate said throttle means to stop said engine.

2. An automatic cutoff device for stopping internal combustion engines at a predetermined speed comprising in combination hydraulic pressure means for interrupting fuel and air feeds to said engine, a .pump for supplying said hydraulic'prs'sure, means for limiting said hydraulic pressure to an inoperative amount, and control means responsive to the speed of said engine -for interrupting the action of said pressure limiting means when said predetermined speed is reached to operate said hydraulic pressure means.

3. An automatic device for cutting olt fuel and air feeds to an internal combustion engine at a predetermined speed of said engine comprising in combination hydraulically actuated throttle means for interrupting said fuel and air feeds to said engine, a pump driven by said engine for supplying hydraulic fluid to said throttle means, and control means responsive to the speed of said engine for increasing the pressure of hydraulic fluid supplied at said throttle means to actuate said throttle means when said predetermined engine s'peed'is reached.

4. An automatic device for cutting off fuel and air feeds to an internal combustion engine at a predetermined engine speed comprising in combination throttle means for interrupting said fuel and air feeds, hydraulic oylind'enand-piston means for closing said throttle means upon increase of pressure of hydraulic fluid in said cylinder-and-piston means, a pump for supplying hydraulic fluid to said cylinder-and-piston means, and control means responsive to the speed of said engine for increasing the pressure of said hydraulic fluid in said cylinder-and-piston means when said predetermined speed is reached to close said throttle means.

5. In a cutofi device for automatically interrupting fuel and air feeds to an internal combustion engine at a predetermined engine speed, the combination which comprises hydraulic cylinder-and-piston throttle means for interrupting said fuel and air feeds, spring means urging said throttle means into open position, a pump for supplying hydraulic fluid to said throttle means, pressure relief means for maintaining the hydraulic pressure in said cylinder-and-pi'ston means at a pressure less than will overcome the force of said spring means, and control means responsive to the speed of said engine for interrupting said pressure relief means when said predetermined engine speed is reached to build up sufiicient hydraulic pressure in said throttle means for overcoming the force of said spring means and moving said throttle means into closed position.

6. In a cutoff device for automatically interrupting fuel and air feeds to an internal combustion engine at a predetermined engine speed, the combination which comprises throttle means for interrupting said fuel and air feeds, a piston for closing said throttle means, a cylinder in which said piston operates, spring means for urging said piston into the open position of said throttle means, a pump for supplying fluid under pressure, a conduit leading said fluid from said pump into said cylinder to operate said piston, a return line leading said fluid out of said cylinder for maintaining the pressure in said cylinder less than that necessary to overcome the force of said spring means, and control means responsive to the speed of said engine for interrupting flow of said fluid out of said cylinder when said predetermined engine speed is reached.

7. In an automatic device for cutting 01f fuel and air feeds to an internal combustion engine at a predetermined engine speed, the combination which comprises throttle means for cutting off said fuel and air feeds, a piston for closing said throttle means, a hydraulic cylinder in which said piston operates, spring means for urging said piston into the open position of said throttle means, a pump driven by said engine for supplying hydraulic fluid under pressure, a conduit for leading said fluid from said pump into said cylinder to operate said piston, a return line for leading said fluid out of said cylinder to maintain the pressure in said cylinder at less than that necessary to overcome the force of said spring means, and control means responsive to the speed of said engine for shutting ofl said return line when said predetermined engine speed is reached whereby suflicient pressure is built up in said cylinder by said pump to overcome said spring means and close said throttle means.

8. In an automatic device for cutting ofi fuel and air feeds to an internal combustion engine at a pre etermined engine speed, the combination which comprises throttle means for cutting off said fuel and air feeds, a piston for closing said throttle means, a hydraulic cylinder in which said piston operates, spring means for urging said piston into the open position of said throttle means, a pump driven by said engine for supplying hydraulic fluid under pressure, a conduit for leading said fluid from said pump into said cylinder to operate said piston, a return line for leading said fluid out of said cylinder to maintain the pressure in said cylinder at less than that necessary to overcome the force of said spring means, means for cutting off said return line to build up in said cylinder suflicient pressure to overcome the force of said spring means, and control means responsive to the speed of said engine for automatically actuating said return line cutoff means when said predetermined engine speed is reached.

9. In an automatic device for cutting ofi fuel and air feeds to an internal combustion engine at a predetermined engine speed, the combination which comprises throttle means for cutting off said fuel feed, additional throttle means for cutting oif said air feed, a fluid pressure activated cylinder-and-piston for closing each said throttle means, spring means for urging each said throttle means into open position, a pump for supplying fluid under pressure, a conduit for leading said fluid from said pump to operate each said cylinder-and-piston, a return line for leading said fluid away from said cylinders-and-pistons to maintain the fluid pressure therein at less than that necessary to overcome the force of said spring means, valve means for cutting off said return line to build up suflicient pressure at said cylinders-and-pistons to move all said throttle means into closed position against the action of said spring means, and control means automatically responsive to the speed of said engine for actuating said valve means to cut off flow in said return line when said predetermined engine speed is reached.

10. In an automatic device for cutting off fuel and air feeds to an internal combustion engine at a predetermined engine speed, the combination which comprises throttle means for interrupting said fuel and air feeds, fluid pressure cylinder-and-piston means for closing said throttle means, spring means for urging said throttle means into open position, means for supplying fluid under pressure to operate said cylinder-and-piston means, a conduit for relieving fluid pressure in said cylinder-and-piston means to maintain the pressure therein at less than that necessary to overcome the force of said spring means, a valve for cutting off flow in said conduit, means urging said valve into closed position, means for locking said valve in open position, and automatic means responsive to the speed of said engine for disengaging said locking means when said predetermined engine speed is reached to close said valve.

11. In a cutoflf device for automatically interrupting fuel and air feeds to an internal combustion engine at a predetermined engine speed, the combination which comprises hydraulically clo-seable throttle means for said fuel and air feeds, means for supplying hydraulic pressure to close said throttle means, means for relieving hydraulic pressure from said throttle means to prevent operation thereof into closed position, and control means automatically responsive to the speed of said engine for cutting off said pressure relief means when said predetermined engine speed is reached for operation of said throttle means into closed position by said hydraulic pressure.

12. In a cutoff device for automatically interrupting fuel and air feeds to an internal combustion engine at a predetermined engine speed, the combination which comprises hydraulically actuated throttle means for said fuel and air feeds, means for supplying hydraulic pressure to operate said throttle means into closed position, means for relieving fluid pressure from said throttle means to prevent suflicient accummulation of pressuretherein for operation thereof into closed position, automatic control means responsive to the speed of said engine for interrupting said pressure relief means when said predetermined engine speed is reached, and manual control means independent of said automatic control means for interrupting said pressure relief means regardless of the speed of said engine both said last mentioned means effecting accumulation of sufficient pressure in said throttle means for operation thereof into closed position to stop said engine.

13. A cutoff device for automatically interrupting fuel and air feeds to an internal combustion engine at a predetermined engine speed comprising in combination fluid pressure actuated throttle means operable from an open position during operation of said engine to a closed position interrupting said fuel and air feeds, means for supplying fluid pressure to operate said throttle means into said open position, spring means urging said throttle means to said closed position, means for relieving fluid pressure from said throttle means effecting operation thereof in said open position by said spring means, and automatic actuating means responsive to the speed of said engine for controlling said pressure relief means effecting increase of pressure for automatic operation of said throttle means from said open position to said closed'position when said predetermined engine speed is reached.

References Cited in the file of this patent UNITED STATES PATENTS 1,166,281 Ver Planck Dec. 28, 1915 1,846,654 Prechtel Feb. 23, 1932 2,260,576 Maybach Oct. 28, 1941 2,606,542 Wallace Aug. 12, 1952 FOREIGN PATENTS 536,805 Great Britain May 28, 1941 

